Optical disc and method of protecting same

ABSTRACT

An optical disc for storage and retrieval of digital data, and a system and method for protecting the optical disc is disclosed. The optical disc has projections or embossments on one or both surfaces. When the optical disc is placed on a substantially flat surface such as a tabletop or a desktop, the projections act as pedestals that elevate the optical disc above the flat surface. The resulting gap or clearance helps prevent damage to the optical disc caused by contaminants on the flat surface or by defects in the flat surface. The projections are sized to provide adequate clearance between the disc and the flat surface, while minimizing interference between the projections and components of optical disc readers and drives. The optical disc may also include one or more depressions that are sized and configured to receive projections from another disc, which facilitates stacking of the optical discs.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No.60/270,434, filed Feb. 21, 2001.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an optical disc for storage andretrieval of digital data and to a method of protecting the opticaldisc.

2. Discussion

Optical discs, such as compact discs (CDs) and digital videodiscs(DVDs), have become the accepted medium for storing and retrieving largeamounts of digital information (data). Standard CDs and DVDs have thesame physical dimensions (12 cm OD, 1.2 mm thickness), but differprimarily in the amount of data that each can hold. A standard CD canstore up to about 783 megabytes of audio programming, while DVDs canhold between about 4.38 gigabytes (single-sided/single-layer DVD) andabout 15.9 gigabytes (double-sided/dual-layer DVD) of multimediaprogramming (photographs, video, audio, etc.). Other optical storagediscs include read only memory compact discs (CD-ROMs), recordablecompact discs (CD-R), recordable DVDs (DVD-R), and rewritable compactdiscs (CD-RW). Though physically similar to audio CDs, CD-ROMs, CD-Rsand CD-RWs can store slightly less data (i.e., less than about 700megabytes) because a fraction of their respective storage capacities areused by a file system and data associated with enhanced errorcorrection.

Optical discs owe their large storage capacity to the way they representdigital data. With CDs and single-layer DVDs, digitized (binary) dataare encoded on the discs as a sequence of microscopic pits separated bysmooth areas (lands) that define a continuous track that spirals outwardfrom the center of the disc. Adjacent tracks on CDs are 1600 nm apart,and the minimum pit length is 830 nm. DVD's achieve their greaterstorage capacity, in part, by shrinking the distance between adjacenttracks (740 nm) and by decreasing the minimum pit length (400-440 nm).Recordable compact discs and rewritable compact discs employ similardata encoding, except that the “pits” on CD-Rs and CD-RWs are replacedby “dark” spots formed, respectively, on a light-sensitive organic dyelayer or light-excitable crystal layer.

Optical disc readers (CD or DVD players, CD-ROM, CD-R or CR-RW drives,etc.) retrieve data using a laser pickup assembly and a tracking system.During playback, the laser pickup assembly focuses a laser beam on thespinning optical disc, while the tracking system moves the laser pickupassembly outward from the center of the disc. The optical reader adjuststhe angular speed of the disc during data retrieval so that pits andlands of a single track stream past the laser beam at constant linearvelocity. The optical pickup includes a detector (e.g., photodiodearray) which detects any light reflected by the optical disc. Laserlight hitting a land reflects at a higher intensity than laser lighthitting a pit (or dark spot) which scatters the light. The optical discreader translates these temporal changes in detected light intensityinto a stream of binary data.

Optical discs have relatively simple, but elegant construction. Digitalvideodiscs, for example, are composed of one or more layers of plastic(e.g., optical grade polycarbonate) that are individually formed byinjection molding. One surface of each layer contains the encoded dataas a spiral track of microscopic pits and lands, while another surfaceis substantially planar. Prior to assembling the layers, DVDmanufactures cover the surface containing the pits and lands with a thinmetallic layer. The plastic layers that will become the outermost layersof the DVD are coated with semi-reflective gold, while the plasticlayers that will become the innermost layers are coated with aluminum.The use of gold allows the laser pickup assembly to focus laser lightthrough the outer layers onto the inner layers of the DVD. Followingpreparation of the plastic layers, each is coated with acrylic lacquer,pressed together, and cured to form the disc. For single-sided discs, alabel is applied onto the non-readable side (i.e., side opposite thepolycarbonate layer or layers containing pits and lands). Audio CD andCD-ROMs are made in a similar manner, but comprise a singlepolycarbonate layer laminated to a metallic film and relatively thinacrylic layer.

Compared to competing technologies such as magnetic storage media,optical discs are mechanically robust and inexpensive. Despite theseadvantages, however, optical discs can be improved. Although thepolycarbonate plastic layer has excellent optical properties and gooddimensional stability, it can be scratched during handling, which maycompromise data stored on the disc. For example, after removing compactdiscs from their protective cases, users often place them oncomparatively hard flat surfaces, such as a tabletop or desktop, withthe polycarbonate or readable side face down (label-side face up). Sinceoptical discs are quite thin, users find it difficult to pickup CDswithout dragging them across the tabletop. In doing so, hardcontaminants on the surface of the tabletop and any defects in thetabletop surface may scratch, gouge, or scuff the polycarbonate plasticlayer. Similarly, users often stack CDs to conserve space. Any dirtparticles trapped between individual CDs may also damage the surfaces ofindividual CDs during handling of the stack. Although the opticalproperties of polycarbonate and on-disc error correction help reduce theaffects of surface scratches, repeated damage to CD surfaces over timemay render some data unreadable.

The present invention overcomes, or at least mitigates, one or more ofthe problems described above.

SUMMARY OF THE INVENTION

The present invention provides an optical disc having projections orembossments on one or both surfaces of the disc. When the optical discis placed on a generally flat surface such as a tabletop or a desktop,the projections act as pedestals that elevate the bulk of the opticaldisc above the flat surface. The resulting gap or clearance enablesusers to grasp and to pick up the optical discs without dragging thediscs across the flat surface. Moreover, even if the optical disc isdragged across the tabletop or desktop, the clearance helps preventdamage to the optical disc caused by contaminants on the flat surface orby defects in the flat surface. The projections are sized to provideadequate clearance between the disc and the flat surface, whilepreventing or reducing interference between the projections andcomponents of optical disc readers and drives. The projections may rangein height up to about one mm, i.e., about the thickness of a standardcompact disc (CD) or digital videodisc (DVD), but typically the heightof the projections is about half (0.6 mm) or less than the thickness ofa standard CD or DVD. In addition, the projections are ordinarilyprovided at predefined non-data portions of the optical disc—e.g., inthe program lead-out region or between the clamping region and theprogram lead-in region—so that the projections will not disturb datastorage or retrieval. Generally, however, the projections may be placedin a disc's data storage (program) area if it lacks encoded digitaldata. The optical disc may also include one or more depressions that aresized and configured to receive projections from another disc, whichfacilitates stacking of the optical discs.

The present invention also includes a system and method for protectingan optical disc that is used to store and retrieve digital data. Thesystem includes one or more projections or embossments that may beapplied to a surface of the optical disc. The projections are sized andconfigured to prevent or minimize interference with digital dataretrieval and to provide clearance between the surface of the opticaldisc and a substantially flat surface when the surface of the opticaldisc is placed on the substantially flat surface. Similarly, the methodincludes providing one or more projections on at least one surface ofthe optical disc. Like the inventive system, the projections are sizedand configured to prevent interference with digital data retrieval andto provide clearance between the optical disc and the substantially flatsurface. The projections may be formed during fabrication of the opticaldisc (i.e., by injection molding) or may be applied to the surface ofthe optical disc by bonding techniques.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a bottom view of an optical disc having projections orembossments for protecting the optical disc surface.

FIG. 2 shows an enlarged partial cross section of the optical discthrough section line 2 of FIG. 1.

FIG. 3 shows an enlarged partial cross section of the optical discthrough section line 3 of FIG. 1.

FIG. 4 shows a side view of a stack of two optical discs resting on aflat surface such as a tabletop or desktop.

FIG. 5 shows the placement of an optical disc having clearanceprojections or embossments within a section of an optical disc reader orplayer.

FIG. 6 is a bottom view of an optical disc having projections orembossments that are applied following fabrication of the optical disc.

FIG. 7 shows an enlarged partial cross section of the optical discthrough section line 7 of FIG. 6.

FIG. 8 is a bottom view of another embodiment of an optical disc havingprojections or embossments that may have different physicalcharacteristics, including shape, height, and orientation.

DETAILED DESCRIPTION

FIG. 1 shows a bottom view of an optical disc 10 having first 12 andsecond 14 sets of projections or embossments for protecting the opticaldisc 10 from damage (scratches, gouges, scuff marks, etc.). For clarity,we describe various embodiments of the optical disc 10 in terms of astandard audio compact disc (CD), and to a lesser extent, in terms of adigital videodisc (DVD). However, the disclosed invention is not limitedto audio CDs and to DVDs, but applies generally to any optical disc thatis used to store and retrieve digital data, including read only memorycompact discs (CD-ROMs), recordable compact discs (CD-R), recordableDVDs (DVD-R), rewritable compact discs (CD-RW), high density fluorescentmultilayer (FMD) ROM media, and the like.

The optical disc 10 shown in FIG. 1 is comprised of a pair ofsubstantially parallel first 16 and second 18 surfaces. As shown in FIG.1, the first 16 and second 18 surfaces have substantially circular andconcentric outer 20 and inner 22 peripheries, although generally theoptical disc's outer periphery may assume any shape. As noted above,digitized (binary) data are encoded on the optical disc 10 as a sequenceof microscopic pits (or dark spots) interrupted by smooth areas (lands)that define a continuous track (or concentric tracks) spiraling outwardfrom the center of the disc 10. In the embodiment shown in FIG. 1, theencoded data lies within a data storage (program) area 24 that can beaccessed by shining laser light through the substantially transparentfirst (bottom) surface 16. The data storage area 24 is defined by alead-in area 26 and a lead-out area 28, which are located adjacent tothe inner 22 and outer 20 peripheries of the first surface 16,respectively. For a standard audio CD, the lead-in and lead outer areasbegin, respectively, at radii 23 mm and 58 mm, and end at radii 25 mmand 60 mm. The lead-in area 26 typically contains digital silence (nodata) in the main channel plus the optical disc's table of contents inthe subcode Q-channel; the lead-out area 28 usually contains no data.

As can be seen in FIG. 1, the first 12 and second 14 sets of projectionsare located in predefined non-data regions of the optical disc 10. Thus,the first set of projections 12 is located on the optical disc's firstsurface 16 within the lead-out area 28. Similarly, the second set ofprojections 14 is located on the optical disc's first surface 16 betweena clamping region 30 and the lead-in area 26. The clamping region 30generally refers to a portion of the optical disc 10 that contacts adisc drive mechanism during playback or recording (see FIG. 5). Instandard CDs and DVDs, a ridge, which is known as a stacking ring 32,encircles the inner periphery 22 of the optical disc 10 and limits theouter radius of the clamping region 30. In some embodiments, the secondset of projections 14 may replace the stacking ring 32.

Each set of projections 12, 14 shown in FIG. 1 is comprised of fourdiscrete and elongated projections 12, 14, although the number ofindividual projections and their distribution may vary among opticaldiscs. The sets of projections 12, 14 shown in FIG. 1 are evenlydistributed within the lead-out area 28 and adjacent to the lead-in area26, which helps stabilize the (rotating) optical disc 10 during playbackand recording. Furthermore, each set of projections 12, 14 are offset,such that any individual second projection 14 lies about midway betweenrays of an angle formed by the center of the optical disc 10 and twoadjacent first projections 12. This latter arrangement should provide amore uniform clearance between the optical disc 10 and any flat surfacethe disc 10 is placed on. Thus, for a given set of projections (e.g.first set of projections 12), it is often desirable to arrange theprojections so that the angular displacement between any two adjacentprojections is about 2π/n, where n is the number of projectionsbelonging to that set. In addition, it is generally desirable to offsetthe first 12 and second 14 projections so that the angular displacementbetween adjacent first 12 and second 14 projections is π/n radians. Inthis way the projections' center of mass lies near the optical disc'srotation center (i.e., within its inner periphery).

In other embodiments, the optical disc 10 may include the first set ofprojections 12, but no second set of projections 14, or may include thesecond set of projections 14, but no first set of projections 12. Inaddition, the optical disc 10 may include more than two sets ofprojections (FIG. 8). The optical disc may employ projections having anydesirable shape, including spherical sections, spheroidal sections,ellipsoidal sections, tetrahedrons, quadrahedrons, pentahedrons,hexahedrons, etc. Besides the discrete projections 12, 14 shown in FIG.1, the optical disc may additionally or alternatively include one ormore continuous projections that circumscribe the inner periphery 22 ofthe optical disc, similar to the stacking ring 32 located adjacent tothe clamping region 30. However, the continuous projections aresubstantially larger than the stacking ring 32, such that when theoptical disc 10 is placed on a flat surface, a gap exists between theflat surface and the bottom surface 16 of the optical disc 10.

Although it is usually desirable to locate projections within thepredefined non-data areas, the projections or embossments may also belocated in areas that are usually reserved for data storage. Forexample, projections may be located within the data storage area 24adjacent to the lead-out area 28, as long as the particular optical disccontains no data in that area. This will often be the case when theamount of stored data is less than the optical disc's data storagecapacity since CDs and single-layer DVDs encode data in a track thatspirals outward from the lead-in 26 area.

In general, the projections may be applied or formed on both the first16 and second 18 surfaces of the optical disc 10. Since data is readthrough its first (bottom) surface 16, the optical disc 10 shown in FIG.1 has no projections located on its second (top) surface 18. However,with double-sided DVDs, data can be read through substantiallytransparent bottom and top surfaces. Moreover, even if data is onlyaccessed through the bottom surface, minor scratches on the top (label)surface of audio CDs, CD-ROMs, CD-Rs, and CD-RWs may compromise dataintegrity since the acrylic layer that protects the metallizedreflective layer is much thinner than the polycarbonate layer.

The optical disc 10 of FIG. 1 has first 34 and second 36 depressions onthe second surface 18, which are sized to accommodate the projections12, 14. As can be seen in FIG. 2 and FIG. 3, which show enlarged partialcross sections of the optical disc 10 through section line 2 and sectionline 3, respectively, the depressions 34, 36 are located adjacent to theprojections 12, 14 and facilitate stacking of optical discs. The heightof the projections 12, 14 are greater than the depth of the depressions34, 36 so that a gap or clearance will exist between adjacent opticaldiscs when stacked. Note, however, that it may be desirable to size thedepressions 34, 36 so that the clearance between adjacent optical discsis a small fraction of the optical disc 10 thickness. Also note that theheight of the ridge 32 shown in FIG. 3 is substantially less than theheight of the projections 14.

FIG. 4 shows a side view of a stack 38 of two optical discs 10 restingon a flat surface 40 such as a tabletop or desktop. Although not shownin FIG. 4, the optical discs 10 have depressions 34, 36 such as thoseshown in FIG. 2 and FIG. 3. The projections 12, 14 and depressions 34,36 stabilize the stack 38 of optical discs 10 and minimize the relativemovement of adjacent optical discs 10 that may damage their surfaces 16,18. The height of each of the projections 12, 14 shown in FIG. 1 doesnot vary significantly among projections 12, 14 so that a gap orclearance 42 between the first surface 16 of the optical disc 10 and theflat surface 40 of the tabletop is substantially uniform. Since thedepressions 34, 36 are shallower than the height of the projections 12,14, a gap or clearance 44 between respective first 16 and second 18surfaces of adjacent optical discs is less than the clearance 42 betweenthe optical disc 10 and the flat surface 40. Nonetheless, the clearance44 between adjacent optical discs 10 is sufficient to minimize damage totheir surfaces 16, 18.

In the embodiment shown in FIG. 4, the heights of individual projections12, 14 are comparable to the thickness of the optical disc 10 (i.e.,about one mm). Generally, however, the projections are sized to provideadequate clearance between the optical disc 10 and the flat surface 40,while minimizing interference between the projections 12, 14 andcomponents of optical disc readers and drives. For compact discs andvideodiscs, this corresponds to projection heights less than thethickness of the optical disc, and more typically, to projection heightsabout half or less than the thickness of standard CDs or DVDs.

FIG. 5 shows the placement of an optical disc 10′ having clearanceprojections or embossments within a portion of an optical disc reader 46(player). The optical disc 10′ shown in FIG. 5 includes sets ofprojections 12′ located on both first 16 and second 18 surfaces alongthe outer periphery 20 of the disc 10′. The optical disc reader 46includes an optical disc drive 48 comprised of a motor 50 for rotatingthe optical disc 10′ about an axis 52 containing its center, a platen54, and a cylindrical spindle 56 that is sized to accommodate the innerperiphery (not shown) of the optical disc 10′. The disc drive 48 alsoincludes spring-loaded tabs 58 that force the optical disc 10′ againstthe platen 54 at the clamping region 30, thereby securing the opticaldisc 10′ during playback. The optical disc reader 46 also includes adisc cradle 60 and housing 62, which are shown in cross-section forclarity. As can be seen in FIG. 5, the projections 12′ are sized toprevent interference with the components optical disc reader 46,including the optical disc drive 48, the disc cradle 60 and the opticalreader housing 62.

The projections 12, 12′, 14 and depressions 34, 36 shown in FIG. 1-FIG.5 may be provided in various ways. For example, the projections 12, 12′,14 (and depressions 34, 36) may be formed by injection molding duringfabrication of the optical disc 10, 10′. In addition, the projections12, 12′, 14 or embossments may be applied to an optical disc 10, 10′following its fabrication. Useful application methods include adhesivebonding, thermal welding, friction bonding, interference bonding, andthe like. In some embodiments, the projections 12, 12′, 14 may beapplied as thermosetting or thermoplastic liquid polymers that solidifythrough chemical cross-linking or cooling. In other embodiments, theprojections 12, 12′, 14 may be applied as decals or similarself-adhesive stock material. When applied after fabrication of theoptical disc 10, 10′, the projections 12, 12′, 14 may be supplied inkits that are applied by users of optical discs.

After market suppliers may also provide the projections 12, 12′, 14 byhot stamping. For example, a heated tool (pin, rod, etc.) having therequisite shape may be pressed against the second (top) surface 18 ofthe optical disc 10 of FIG. 1-FIG. 3, forming depressions 34, 36 andcorresponding projections 12, 14 on the second 18 and first (bottom) 16surfaces, respectively.

FIG. 6 is a bottom view of an optical disc 10″ having projections 12″ orembossments that are applied following fabrication of the optical disc10″. The projections 12″ are held in place by an interference fit orfriction bonding. Like the projections 12′ shown in FIG. 1, theprojections 12″ are located within the lead-out area 28 of the opticaldisc 10″, but extend slightly outward from disc's outer periphery 20.

As shown in FIG. 7, which is an enlarged partial cross section throughsection line 7 in FIG. 6, the projections 12″ are located on both thefirst 16 and second 18 surfaces of optical disc 10″. Each projection 12″is made of a resilient material and contains a slot 64, which isslightly smaller than the thickness of the optical disc 10″. To install,individual projections 12″ are clipped onto the outer periphery 20 ofthe optical disc 10″ and are held in place by friction between the walls66 of the slot 64 and the surfaces 16, 18 of the optical disc 10″.

Although on a given optical disc 10, 10′, 10″ the sets of projections12, 12′, 12″, 14, 14′ shown in FIG. 1 through FIG. 7 have similar shape,height, and orientation, other embodiments may include sets ofprojections that have different physical characteristics.

For example, FIG. 8 is a bottom view of an optical disc 10′″ havingfirst 12′″, second 14″, and third 68 sets of projections or embossmentson the first (bottom) surface 16 of the optical disc 10′″. Like the setsof projections 12, 14 shown in FIG. 1, the first 12′″ and second 14″sets of projections are evenly distributed in circular bands within thelead-out area 28 and adjacent to the lead-in area 26, respectively.Additionally, each set of projections 12′″, 14″ are offset, such thatany individual second projection 14″ lies about midway between rays ofan angle formed by the center 70 of the optical disc 10′″ and twoadjacent first projections 12′″. Though both sets of projections 12′″,14″ are shaped like a section of an ellipsoid, their orientations aredifferent. As can be seen in FIG. 8, each of the first set ofprojections 12′″ has a longitudinal (major) axis 72 that issubstantially tangent to a first circle 74 which contains the centers ofthe first set of projections 12′″. In contrast, each of the second setof projections 14′″ has a longitudinal axis 76 that is substantiallynormal to a second circle 78 which contains the centers of the secondset of projections 14′″.

Besides different orientation, the optical disc 10′″ includesprojections having different heights and shapes. For example, each ofthe third set of projections 68 is disposed within the lead-out area 28of the optical disc 10′″, about midway between two adjacent firstprojections 12′″. Unlike the ellipsoidal first 12′″ and second 14″ setsof projections, each of the third set of projections 68 has the shape ofa spherical section. Moreover, though the third set of projections 68have similar sizes, their heights are substantially less than theheights of the first 12′″ and second 14″ sets of projections. Forexample, the first 12′″ and second 14″ sets of projections may haveheights about equal to one half the thickness of a standard CD or DVD(e.g., 0.6 mm). In contrast, the third set of projections 68 may haveheights about equal to one quarter the thickness of a standard CD or DVD(e.g., 0.3 mm).

The differences in orientation, shape, and height among the sets ofprojections 12′″, 14″, 68 may offer some advantages. For instance, theuse of the smaller third set of projections 68 permits greater spacingof the first set of projections 12′″ without significantly affecting theprotection of the first surface 16. When placed on a substantially flatsurface with the optical disc's 10′″ first surface 16 facing the flatsurface, the third set of projections 68 helps maintain a clearancebetween the two surfaces—albeit a smaller clearance than the first setof projections 12′″ provides. The increased spacing of the first set ofprojections 12′″ and the radial orientation of the second set ofprojections 14″, help minimize interference between slot-loading opticaldisc readers and drives and the first 12′″ and second 14″ sets ofprojections. The foregoing are merely some examples of the differentconfigurations that can distinguish various types of projections. Othercharacteristics can be used to distinguish between other types ofprojections. The projections 12′″, 14″, 68 may be provided using any ofthe methods described above. For example, the projections 12′″, 14″, 68may be formed by injection molding during fabrication of the opticaldisc 10′″ or may be applied to the optical disc 10′″ following itsfabrication.

It should be understood that the above description is intended to beillustrative and not limiting. Many embodiments will be apparent tothose of skill in the art upon reading the above description. Therefore,the scope of the invention should be determined, not with reference tothe above description, but instead with reference to the appendedclaims, along with the full scope of equivalents to which such claimsare entitled. The disclosures of all patents, articles and references,including patent applications and publications, if any, are incorporatedherein by reference in their entirety and for all purposes.

What is claimed is:
 1. An optical disc that is used to store andretrieve digital data, the optical disc comprising: first and secondsurfaces having inner and outer peripheries, at least the first surfaceof the optical disc capable of transmitting light; an area for storingdigital data, the area located between the inner and outer peripheriesof the first and second surfaces, the digital data being accessible byshining light through the first surface of the optical disc; one or moreprojections located on at least the first surface of the optical disc,the one or more projections sized and configured to minimizeinterference with retrieving the digital data stored on the optical discand to provide a clearance between the first surface of the optical discand a substantially flat surface when the optical disc is placed on thesubstantially flat surface with the first surface of the optical discfacing the substantially flat surface; and depressions located on thesecond surface of the optical disc.
 2. The optical disc of claim 1,wherein the depressions are sized and configured to accommodate the oneor more projections.
 3. An optical disc having at least a first surface,the disc comprising: a number of discrete projections that are spacedapart on an outer edge of the first surface, wherein the projectionsinclude at least a first type of projection having a first configurationand at least a second type of projection having a second configurationdifferent than the first configuration, wherein the first configurationat least includes a first height and the second configuration at leastincludes a second height.
 4. An optical disc having at least a firstsurface, the disc comprising: a number of discrete projections that arespaced apart on an outer edge of the first surface, wherein theprojections include at least a first type of projection having a firstconfiguration and at least a second type of projection having a secondconfiguration different than the first configuration, wherein the firstconfiguration at least includes a first shape and the secondconfiguration at least includes a second shape.
 5. An optical dischaving at least a first surface, the disc comprising: a number ofdiscrete projections that are spaced apart on an outer edge of the firstsurface, wherein the projections include at least a first type ofprojection having a first configuration and at least a second type ofprojection having a second configuration different than the firstconfiguration, wherein the first configuration at least includes a firstlength and the second configuration at least includes a second length.6. An optical disc having at least a first surface, the disc comprising:a number of discrete projections that are spaced apart on an outer edgeof the first surface, wherein the projections include at least a firsttype of projection having a first configuration and at least a secondtype of projection having a second configuration different than thefirst configuration, wherein the first configuration at least includes afirst width and the second configuration at least includes a secondwidth.
 7. The optical disc according to claims 3, 4, 5 or 6, wherein thefirst configuration at least includes a first shape and a first heightand the second configuration at least includes a second shape and asecond height.
 8. The optical disc according to claims 3, 4, 5 or 6,further comprising at least a predetermined pattern of first typeprojections and second type projections.
 9. The optical disc accordingto claims 3, 4, 5 or 6, further comprising a predetermined pattern offirst type projections and second type projections, where the first typeprojections and the second type projections are alternately spaced. 10.The optical disc according to claims 3, 4, 5 or 6, further comprising apredetermined pattern of first type projections and second typeprojections, where two second type projections are located between twoadjacent first type projections.
 11. The optical disc according toclaims 3, 4, 5 or 6, further comprising a predetermined pattern of firsttype projections and second type projections, wherein the first typeprojections and the second type projections are alternately spaced, andfurther wherein the first configuration at least includes a first heightand the second configuration at least includes a second height.
 12. Theoptical disc according to claims 3, 4, 5 or 6, further comprising apredetermined pattern of first type projections and second typeprojections, wherein the first type projections and the second typeprojections are alternately spaced, and further wherein the firstconfiguration at least includes a first shape and the secondconfiguration at least includes a second shape.
 13. The optical discaccording to claims 3, 4, 5 or 6, further comprising a predeterminedpattern of first type projections and second type projections, where thefirst type projections and second type projections are alternatelyspaced, and further wherein the first configuration at least includes afirst length and the second configuration at least includes a secondlength.
 14. The optical disc according to claims 3, 4, 5 or 6, furthercomprising a predetermined pattern of first type projections and secondtype projections, where the first type projections and second typeprojections are alternately spaced, and further wherein the firstconfiguration at least includes a first width and the secondconfiguration at least includes a second width.
 15. The optical discaccording to claims 3, 4, 5 or 6, further comprising a predeterminedpattern of first type projections and second type projections, where thefirst type projections and second type projections are alternatelyspaced, and further wherein the first configuration at least includes afirst shape and a first height the second configuration at leastincludes a second shape and a second height.
 16. The optical discaccording to claims 3, 4, 5 or 6, wherein the first configuration atleast includes a first height and the second configuration at leastincludes a second height and wherein the first type projections have apredetermined spacing.
 17. The optical disc according to claims 3, 4, 5or 6, the first configuration at least includes a first height and thesecond configuration at least includes a second height, and wherein thefirst type projections have a predetermined spacing, where the height ofthe first type projections are chosen to increase protection of thefirst surface and the spacing of the first type projections is chosen toreduce interference during loading into a disc player.
 18. The opticaldisc according to claims 3, 4, 5 or 6, wherein the first configurationat least includes a first height and the second configuration at leastincludes a second height, and wherein the first type projections have apredetermined spacing, where the first height is chosen to increaseprotection of the first surface and the spacing of the first typeprojections is chosen to reduce interference during loading into a discplayer and the second height is chosen in relation to the first heightand spacing of the first type projections.
 19. The optical discaccording to claims 3, 4, 5 or 6, wherein the second configuration isadapted to enhance aerodynamics of the projections.
 20. The optical discaccording to claims 3, 4, 5 or 6, further comprising at least third typeprojections near the outer edge, having a third configuration whereinthe first configuration at least includes a first height and the secondconfiguration at least includes a second height and the thirdconfiguration at least includes a third height different than the firstheight and the second height.
 21. The optical disc according to claims3, 4, 5 or 6, further comprising at least a third type of projection andhaving a predetermined pattern of first type projections, second typeprojections and third type projections near the outer edge.
 22. Theoptical disc according to claims 3, 4, 5 or 6, further comprising atleast a third type of projection and having a predetermined pattern offirst type projections, second type projections and third typeprojections near the outer edge, wherein the pattern includes at leastone sequence of the first type projection adjacent to the second typeprojection, adjacent to the third type projection, adjacent to thesecond type projection, adjacent to the first type projection.
 23. Theoptical disc according to claims 3, 4, 5 or 6, further comprising atleast a third type of projection and having a predetermined pattern ofthe first type projections, the second type projections and the thirdtype projections near the outer edge, wherein the pattern includes atleast one sequence of the first type projection adjacent to the secondtype projection, adjacent to the third type projection, adjacent to thesecond type projection, adjacent to the first type projection, whereinthe first configuration at least includes a first height, the secondconfiguration at least includes a second height and the thirdconfiguration at least includes a third height, where the first heightis greater than the second height and the second height is greater thanthe third height.
 24. The optical disc according to claims 3, 4, 5 or 6,further comprising at least a third type of projection and having apredetermined pattern of first type projections, second type projectionsand third type projections near the outer edge, wherein the patternincludes at least one sequence of the first type projection adjacent tothe third type projection, adjacent to the second type projection,adjacent to the third type projection, adjacent to the first typeprojection.
 25. The optical disc according to claims 3, 4, 5 or 6,further comprising at least a third type of projection and having apredetermined pattern of first type projections, second type projectionsand third type projections near the outer edge, wherein the patternincludes at least one sequence of the first type projection adjacent tothe third type projection, adjacent to the second type projection,adjacent to the third type projection, adjacent to the first typeprojection, wherein the first configuration at least includes a firstheight, the second configuration at least includes a second height andthe third configuration at least includes a third height, where thefirst height is greater than the second height and the second height isgreater than the third height.
 26. The optical disc according to claims3, 4, 5 or 6, further comprising a predetermined pattern of at least thefirst type projections and the second type projections, wherein adjacentprojections have different configurations.
 27. The optical discaccording to claims 3, 4, 5 or 6, further comprising a predeterminedpattern of at least the first type projections and the second typeprojections, wherein adjacent projections have different heights. 28.The optical disc according to claims 3, 4, 5 or 6, further comprising apredetermined pattern of at least the first type projections and thesecond type projections, wherein adjacent projections have differentshapes.
 29. The optical disc according to claims 3, 4, 5 or 6, furthercomprising a predetermined pattern of at least the first typeprojections and the second type projections, wherein the predeterminedpattern includes at least one sequence of at least two first typeprojections adjacent one another.
 30. The optical disc according toclaims 3, 4, 5 or 6, further comprising a predetermined pattern of atleast the first type projections and the second type projections,wherein the predetermined pattern includes at least one sequence of atleast two second type projections adjacent one another.
 31. The opticaldisc according to claims 3, 4, 5 or 6, further comprising apredetermined pattern of at least the first type projections and thesecond type projections, wherein the pattern includes at least onesequence of at least two first type projections adjacent one another andadjacent to at least two second type projections adjacent one another.32. The optical disc according to claims 3, 4, 5 or 6, wherein at leastone of the first type configuration and the second type configurationcomprises a generally elliptical shape.
 33. The optical disc accordingto claims 3, 4, 5 or 6, wherein the first type projection includes afirst height and wherein the first height is chosen to enhanceprotection of the disc surface and to reduce, to acceptable levels,interference caused by the disc during loading into a disc reader. 34.The optical disc according to claims 3, 4, 5 or 6, wherein the firsttype projection includes a first height and wherein the first height ischosen to enhance protection of the disc surface and to reduce, toacceptable levels, interference caused by the disc during loading into aslot load disc reader.
 35. The optical disc according to claims 3, 4, 5or 6, wherein the optical disc comprises discrete projections spacedapart proximate to the outer edge and an inner periphery.
 36. Theoptical disc according to claims 3, 4, 5 or 6, further comprises aninner periphery and wherein discrete projections are spaced apartproximate to the outer edge and the inner periphery and further whereinprojections proximate to the outer edge and inner periphery are radiallyaligned.
 37. The optical disc according to claims 3, 4, 5 or 6, furthercomprises an inner periphery and wherein discrete projections are spacedapart proximate to the outer edge and the inner periphery and furtherwherein projections proximate to the outer edge and inner periphery areradially offset.
 38. The optical disc according to claims 3, 4, 5 or 6,further comprises an inner periphery and wherein discrete projectionsare spaced apart proximate to the outer edge and the inner periphery andfurther wherein projections proximate to the outer edge and innerperiphery have no predetermined radial alignment.
 39. The optical discaccording to claims 3, 4, 5 or 6, wherein the optical disc furthercomprises an inner periphery and wherein discrete projections are spacedapart proximate to the outer edge and the inner periphery and furtherwherein projections on the inner periphery are located at a positionthat bisects an angle formed by two adjacent projections orientedproximate to the outer edge.
 40. The optical disc according to claims 3,4, 5 or 6, further comprising projections positioned on an innerperiphery, wherein the projections are formed by heat stamping.
 41. Theoptical disc according to claims 3, 4, 5 or 6, further comprisingprojections positioned on an inner periphery, wherein the projectionsare formed during disc fabrication.
 42. The optical disc according toclaims 3, 4, 5 or 6, further comprising projections positioned on aninner periphery, wherein the projections are formed during discfabrication by injection molding.
 43. The optical disc according toclaims 3, 4, 5 or 6, further comprising projections positioned on aninner periphery, wherein the projections are formed during discfabrication by a thermo set liquid polymer.
 44. The optical discaccording to claims 3, 4, 5 or 6, further comprising projectionspositioned on an inner periphery, wherein the projections are formedduring disc fabrication by a thermoplastic liquid polymer.
 45. Theoptical disc according to claims 3, 4, 5 or 6, further comprisingprojections positioned on an inner periphery, wherein the projectionsare formed during disc fabrication by application of decals.
 46. Theoptical disc according to claims 3, 4, 5 or 6, further comprisingprojections positioned on an inner periphery, wherein the projectionsare formed during disc fabrication by application of self-adhesionstock.
 47. The optical disc according to claims 3, 4, 5 or 6, whereinthe disc comprises an inner periphery having a stacking ring area andprojections that are located on the stacking ring area of the disc. 48.The optical disc according to claims 3, 4, 5 or 6, wherein the disccomprises an inner periphery having a structurally reinforced area andprojections located on the structurally reinforced area of the disc. 49.The optical disc according to claims 3, 4, 5 or 6, wherein the disccomprises an inner periphery having a lead-in area and projections thatare located proximate to the lead-in area of the disc.
 50. The opticaldisc according to claims 3, 4, 5 or 6, wherein the disc comprises alead-out area proximate to the outer edge and wherein projections arelocated on the lead-out area of the disc.
 51. The optical disc accordingto claims 3, 4, 5 or 6, wherein the disc comprises a lead-out areaproximate to the outer edge and wherein projections are located on thelead-out area of the disc, but spaced from an inner most edge of thelead-out area.
 52. The optical disc according to claims 3, 4, 5 or 6,further comprising a lead-in area and a lead out area and whereindiscrete projections are placed on the lead-out area and adjacent to thelead-in area.
 53. The optical disc according to claims 3, 4, 5 or 6,further comprising data areas, a lead-in area and a lead-out area andwherein discrete projections are placed on the lead-out area andadjacent to the lead-in area and wherein a distance between projectionslocated adjacent to the lead-in area and lead-out area is minimizedwithout interfering with data areas of the disc.
 54. The optical discaccording to claims 3, 4, 5 or 6, further comprising data areas, alead-in area and a lead-out area, wherein discrete projections areplaced on the lead-out area and adjacent to the lead-in area and whereina distance between projections placed adjacent to the lead-in area andon the lead-out area is minimized without interfering with data areas ofthe disc, while reducing potential for interference with a laser head ofa disc reader into which the disc is loaded.
 55. The optical discaccording to claims 3, 4, 5 or 6, further comprising discreteprojections spaced apart proximate to the outer edge and an innerperiphery, wherein a tallest projection type on the inner periphery andouter edge have a same height, wherein the height is chosen to reducewarping if the disc is exposed to a heat source.
 56. The optical discaccording to claims 3, 4, 5 or 6, wherein the optical disc comprisesdiscrete projections spaced apart proximate to the outer edge and aninner periphery, wherein the projections proximate to the outer edge andinner periphery have different heights.
 57. The optical disc accordingto claims 3, 4, 5 or 6, wherein the optical disc comprises discreteprojections spaced apart proximate to the outer edge and an innerperiphery, wherein the number of projections proximate to the outer edgeare greater than number of projections on the inner periphery.
 58. Theoptical disc according to claims 3, 4, 5 or 6, wherein the optical disccomprises discrete projections spaced apart proximate to the outer edgeand an inner periphery and wherein there exists radial alignment betweenthe projections proximate to the outer edge and inner periphery.
 59. Theoptical disc according to claims 3, 4, 5 or 6, wherein the optical disccomprises discrete projections spaced apart proximate to the outer edgeand an inner periphery and wherein there exists no radial alignmentbetween the projections proximate to the outer edge and inner periphery.60. The optical disc according to claims 3, 4, 5 or 6, wherein theoptical disc comprises discrete projections spaced apart proximate tothe outer edge and an inner periphery and wherein projections on theinner periphery bisect an angle between two adjacent projectionsproximate to the outer edge.
 61. The optical disc according to claims 3,4, 5 or 6, wherein the optical disc comprises discrete projectionsspaced apart proximate to the outer edge and an inner periphery andwherein there exists no pre-specified alignment between projectionslocated proximate to the outer edge and the inner periphery.
 62. Theoptical disc according to claims 3, 4, 5 or 6, wherein the optical disccomprises discrete projections spaced apart proximate to the outer edgeand an inner periphery and wherein projections on the inner peripheryare formed on a stacking ring of the disc.
 63. The optical discaccording to claims 3, 4, 5 or 6, wherein the optical disc comprisesdiscrete projections spaced apart proximate to the outer edge and aninner periphery and wherein projections on the inner periphery areformed on a structurally reinforced area of the disk.
 64. The opticaldisc according to claims 3, 4, 5 or 6, wherein the optical disccomprises discrete projections spaced apart proximate to the outer edgeand an inner periphery and wherein inner projections are formedproximate to a lead-in area defined on the disc.
 65. The optical discaccording to claims 3, 4, 5 or 6, wherein the optical disc comprisesdiscrete projections spaced apart proximate to the outer edge and aninner periphery and wherein projections proximate to the outer edge areformed in a lead out zone defined on the disc.
 66. The optical discaccording to claims 3, 4, 5 or 6, wherein the optical disc comprisesdiscrete projections spaced apart proximate to the outer edge and aninner periphery and wherein projections proximate to the outer edge areplaced on the lead-out area, but spaced from an inner most edge oflead-out area to prevent collision with the laser head.
 67. The opticaldisc according to claims 3, 4, 5 or 6, wherein the optical disccomprises discrete projections spaced apart proximate to the outer edgeand an inner periphery and wherein discrete projections are placed onthe lead-out area and proximate to the lead-in area.
 68. The opticaldisc according to claims 3, 4, 5 or 6, wherein the optical disccomprises discrete projections spaced apart proximate to the outer edgeand an inner periphery and wherein a distance between projectionslocated proximate to the outer edge and inner periphery is minimizedwithout interfering with data areas.
 69. The optical disc according toclaims 3, 4, 5 or 6, wherein the optical disc comprises discreteprojections spaced apart proximate to the outer edge and an innerperiphery and wherein a distance between projections located proximateto the outer edge and inner periphery is minimized without interferingwith data areas and while minimizing potential for interference with alaser head.
 70. The optical disc according to claims 3, 4, 5 or 6,wherein the optical disc comprises discrete projections spaced apartproximate to the outer edge and an inner periphery and whereinprojections located proximate to the outer edge and inner periphery havea same height that is chosen to reduce warping if the disk is exposed toa heat source.
 71. The optical disc according to claims 3, 4, 5 or 6,wherein the optical disc comprises discrete projections spaced apartproximate to the outer edge and an inner periphery and whereinprojections located proximate to the outer edge and inner periphery havedifferent heights.
 72. The optical disc according to claims 3, 4, 5 or6, wherein the optical disc comprises discrete projections spaced apartproximate to the outer edge and an inner periphery and wherein a numberof projections proximate to the outer edge is greater than a number ofprojections on the inner periphery.
 73. The optical disc according toclaims 3, 4, 5 or 6, wherein the optical disc comprises elongatedprojections proximate to the outer edge, where the direction ofelongation is approximately perpendicular to a radius of the disc. 74.The optical disc according to claims 3, 4, 5 or 6, wherein the opticaldisc comprises elongated projections proximate to the outer edge and noprojections are provided on an inner periphery.
 75. The optical discaccording to claims 3, 4, 5 or 6, wherein the optical disc compriseselongated projections proximate to the outer edge and further comprisesprojections on the inner periphery.
 76. The optical disc according toclaims 3, 4, 5 or 6, wherein the optical disc comprises elongatedprojections proximate to the outer edge, the elongated projectionshaving at least two configurations.
 77. The optical disc according toclaims 3, 4, 5 or 6, wherein the optical disc comprises at least twoprojection types proximate to the outer edge, each having apredetermined configuration, wherein each of the two projection typescomprise a different size.
 78. The optical disc according to claims 3,4, 5 or 6, wherein the optical disc comprises at least two projectiontypes proximate to the outer edge, each having a predeterminedconfiguration, wherein each of the two projection types includesprojections elongated in a direction perpendicular to radius.
 79. Theoptical disc according to claims 3, 4, 5 or 6, wherein the optical disccomprises at least two projection types proximate to the outer edge,wherein the first type of projection comprises an elongate projectionand the second type of projection comprises a spherical shape.
 80. Theoptical disc according to claims 3, 4, 5 or 6, wherein the optical disccomprises at least two projection types proximate to the outer edge,wherein the first type of projection comprises an elongate projectionand the second type of projection comprises a shape smaller than theelongate projection.
 81. The optical disc according to claims 3, 4, 5 or6, wherein the optical disc comprises at least two projection typesproximate to the outer edge, wherein the first type of projectioncomprises an elongate projection and the second type of projectioncomprises a shape smaller than the elongate projection, wherein theshape maximizes a mass of the second type of projection while minimizingthe side profile in relation to slot load drives.
 82. The optical discaccording to claims 3, 4, 5 or 6, wherein the optical disc comprisesdiscrete projections spaced apart proximate to the outer edge and aninner periphery and wherein the projections proximate to the outer edgeare positioned approximately tangent to the outer edge of the disc andprojections on the inner periphery are approximately perpendicular to aninner edge of the disc.
 83. The optical disc according to claims 3, 4, 5or 6, wherein the optical disc comprises discrete projections spacedapart proximate to the outer edge and an inner periphery and whereinalternating projections proximate to the outer edge are positionedapproximately tangent to the outer edge of the disc and projections onthe inner periphery are approximately perpendicular to an inner edge ofthe disc.
 84. The optical disc according to claims 3, 4, 5 or 6, whereinthe projections are oriented to facilitate loading in slot load drives.85. The optical disc according to claims 3, 4, 5 or 6, wherein the firsttype of projections are spaced to facilitate loading in slot load drivesand more projections of the second type are provided between the firsttype of projections to reduce contact between disc surface and apotentially damaging surface.
 86. The optical disc according to claims3, 4, 5 or 6, wherein the first type of projections have a heightgreater than that of the second type of projections.
 87. The opticaldisc according to claims 3, 4, 5 or 6, wherein the second type ofprojections are configured to not interfere with loading into slot loaddrives.
 88. The optical disc according to claims 3, 4, 5 or 6, whereinthe first type of projections are approximately ½ to ¼ the height of thedisc.
 89. The optical disc according to claims 3, 4, 5 or 6, wherein thefirst type of projections are approximately ½ to ¼ the height of thedisc and the second type of projections are approximately ½ to ⅔ of theheight of the first type of projections.
 90. The optical disc accordingto claims 3, 4, 5 or 6, wherein the first type of projections areapproximately ½ to ¼ the height of the disc and the second type ofprojections are approximately ½ to ⅔ of the height of first type ofprojections and any additional types of projections are equal to or lessthan the height of the first type of projections.
 91. The optical discaccording to claims 3, 4, 5 or 6, wherein the first type of projectionsare approximately 0.6 mm to 0.3 mm in height and the height of the discis approximately 1.2 mm.
 92. The optical disc according to claims 3, 4,5 or 6, wherein the first type of projections are approximately 0.6 mmto 0.3 mm in height and the height of the disc is approximately 1.2 mmand the second type of projections are approximately ½ to ⅔ of theheight of first type of projections.
 93. The optical disc according toclaims 3, 4, 5 or 6, wherein the first type of projections areapproximately 0.6 mm to 0.3 mm in height and the height of the disc isapproximately 1.2 mm and the second type of projections areapproximately ½ to ⅔ of the height of first type of projections and anyadditional types of projections are equal to or less than the height ofthe first type of projections.
 94. The optical disc according to claims3, 4, 5 or 6, wherein the optical disc is approximately 1.2 mm thick anda first type of projections is placed proximate to the outer edge andare approximately 0.45 mm high.
 95. The optical disc according to claims3, 4, 5 or 6, wherein the optical disc comprises projections on the atleast one surface and complimentary indentations on an opposite surface.96. The optical disc according to claims 3, 4, 5 or 6, wherein theoptical disc comprises projections on the at least one surface andcomplimentary indentations on an opposite surface to facilitate stackingof discs.
 97. The optical disc according to claims 3, 4, 5 or 6, furthercomprising a predetermined pattern of first type projections and secondtype projections, wherein the first type projections and second typeprojections are alternately spaced to allow for the increased spacing ofa primary projection set comprising one of the first type projectionsand the second type projections.
 98. The optical disc according toclaims 3, 4, 5 or 6, further comprising a predetermined pattern of firsttype projections and second type projections, wherein the first typeprojections and second type projections are alternately spaced to allowfor increased spacing of a primary projection set comprising one of thefirst type projections and the second type projections, to reducedinterference when loading into a slot load player.
 99. The optical discaccording to claims 3, 4, 5 or 6, further comprising a predeterminedpattern of first type projections and second type projections, whereinthe first type projections and the second type projections arealternately spaced to allow for the increased spacing of a primaryprojection set comprising one of the first type projections and thesecond type projections, to reduce a side profile of the projections.100. The optical disc according to claims 3, 4, 5 or 6, furthercomprising a predetermined pattern of first type projections and secondtype projections, wherein the first type projections and second typeprojections are alternately spaced to allow for the increased spacing ofa primary projection set comprising one of the first type projectionsand the second type projections, to reduce a total number of primaryprojections needed.
 101. The optical disc according to claims 3, 4, 5 or6, further comprising a predetermined pattern of first type projectionsand second type projections, where the first type projections and secondtype projections are alternately spaced, and further wherein the firstconfiguration includes a first width and the second configurationincludes a second width.
 102. The optical disc according to claims 3, 4,5 or 6, further comprising at least a third type of projection having athird configuration wherein the first configuration includes a firstheight and the second configuration includes a second height, and theprojections having the third configuration are located proximate to theouter edge and have a height that is the same as the second height. 103.The optical disc according to claims 3, 4, 5 or 6, further comprising atleast a third type of projection having a third configuration whereinthe first configuration includes a first height and the secondconfiguration includes a second height and the projections having thethird configuration are located proximate to the outer edge and have aheight the same as the second height, and wherein the projections havedifferent shapes.
 104. The optical disc according to claims 3, 4, 5 or6, wherein the first type of projections have the same height as thesecond type of projections.